photography - What causes the bright white area in this photo of the earth?

Taken on March 28 2012 by André Kuipers, the version here is labeled

Amazing aurora lights and atmospheric glare with the countries Ireland, Netherlands, Scotland, England and Wales in the foreground.

Off to the north and east like that, it's likely refracted early sunrise. That's a lot of streetlights for that time of the day; likely a longish exposure to capture aurora. That'd increase sunrise glare as well.